The effect of dietary factors, including calorie content and food type, on fasting hyperbilirubinemia will be determined using ponies with biliary fistulas as the primary model. This should help clarify the effect of diet on hepatic function observed in many animals and man. Hepatic clearance and turnover of bile acids will be studied in normal and mutant Southdown and Corriedale sheep with inherited transport defects like those found in man. The transport and metabolism of other anions, like sulfobromophthalein, will also be studied in those sheep. BIBLIOGRAPHIC REFERENCES: Anwer, M.S., Gronwall, R. A Compartmental Model for Bilirubin Kinetics in Isolated Perfused Rat Liver. Can. J. Physiol. Pharm. 54: 277-286 (1976). Anwer, M.S.; Engelking, L.R.; Gronwall, R.; Klentz, R.D. Plasma Bile Acid Elevation Following CC14 Induced Liver Damage in Dogs, Sheep, Calves, and Ponies. Res. Vet. Sci. 20: 127-130 (1976).